Is a Skyline a Gtr?

Skyline are the pre 35 modells. ALL Skylines and the R35, which also got the subname "GTR" are AWD. Thats what the GTR mainly stands for. Since there are no RWD versions of the R35, there is no need for the name Skyline anymore.

Is an R34 GT-R a Skyline?

The R34 Skyline GT-R was introduced in 1998, and was available from 1998 to 2002. A technologically advanced display unit set the model apart, while it's RB26DETT twin-turbo I6 engine produced impressive horsepower.

Why isn't the GT-R a Skyline?

Previous generation GT-Rs (e.g. R32/R33/R34) were based on the Skyline platform of that generation. ... The GT-R name was kept because the R35 GT-R is really the spiritual successor to the Skyline GT-Rs of old, but Nissan chose not to use the Skyline name because of the unique platform.